This invention relates, in general, to fabricating semiconductor wafers, and more particularly, to a method of reducing the number of defects on semiconductor wafers.
The importance of improving quality is well known in any manufacturing industry. In all steps of semiconductor device manufacturing, care must be taken to ensure that contaminants or impurities are not present on the semiconductor wafer. Cleaning steps are commonly instituted at various places in the manufacture of semiconductor devices to remove impurities which can eventually cause defects. Presently, a solution of hydrochloric acid and peroxide is used by some manufacturers to remove impurities and residue. Another common cleaning solution is hydrofluoric acid and water or buffered hydrofluoric acid and water. A method to remove surface damaged material and give a smooth surface is disclosed in U.S. Pat. No. 3,669,774, issued to Dismukes on June 13, 1972. Here a mechanically polished silicon wafer is etched to prepare the surface for epitaxial silicon growth thereon. The silicon etch takes place at a temperature of approximately 800.degree. to 1050.degree. C., with a gas mixture consisting of H.sub.2 and/or He, and a small concentration of a gas reactive with SiO.sub.2 such as HF, CIF.sub.3, or BrF.sub.5, and a small concentration of a gas reactive with silicon such as HBR, HI, HCl, Cl.sub.2, Br.sub.2, or I.sub.2. This process is somewhat limited in that the temperature must be elevated between 800.degree. and 1050.degree. C. and because gases are used, the reaction must take place in an enclosed reactor.
The struggle to remove impurities in semiconductor device manufacture begins with the fabrication of single crystal silicon. Silicon crystals or ingots are sliced, lapped and polished to form wafers. In the process of shaping these wafers, impurities and defects may be incorporated into and on the silicon wafer. These defects may cause failures in the semiconductor devices. The removal of the impurities and defects would not only increase the number of good wafers produced, but also increase the number of good devices fabricated per wafer. A simple method of removing impurities that can be carried out at room temperature is desirable.
By now it should be appreciated that it would be advantageous to provide a process that reduces the amount of defects on semiconductor wafers, thus improving the quality and yield of semiconductor devices.
Accordingly, it is an object of the present invention to provide a method to remove the impurities from semiconductor wafer surfaces.
Another object of the present invention is to provide a method to reduce the number of defects on semiconductor wafers.
A further object of the present invention is to provide a method that imporves the quality and yield of semiconductor devices.